When i run the first petittion of a bean's method (let's say method A) on the server everything seems ok, but when running for the second time any petition on this carrierRESTWS bean (let's say method B), the dao being used is the same carrierDAO instance. How can i avoid having this problem and making the injection use a new instance of the dao each time this carrierRESTWS bean is being called?
Beans configuration inside xml file:
<bean id="carrierRESTWS" class="ar.com.anovo.controllers.rest.CarrierRESTWS">
<property name="carrierDAO" ref="carrierDAO"/>
</bean>
<bean id="carrierDAO" class="ar.com.anovo.dao.CarrierDAO"></bean>
Set the scope of "carrierDAO" to "prototype":
<bean id="carrierDAO" class="ar.com.anovo.dao.CarrierDAO" scope="prototype" />
This will create a new instance, once an injection is required.
More about scopes can be found in the Spring Doc.
Your beans are singleton beans, so they live for as long as the Spring Container lives, which basically means for as long as your program is running, which again means for as long as your webapp is running, which could theoretically be years.
Since your controllers and your DAO classes have of course been coded to be stateless, and support multi-threading, you shouldn't have a problem with a single shared instance.
The default scope in spring is singleton, so you need to explicitly set the scope which makes a new instance each time as #Stefan indicates with prototype.
Related
Is there a way to enforce the initialization of a Spring Bean in cases that the reference of the bean is never explicitly used or even requested in the ApplicationContext?
<bean class="foo.bar.FooBar>
<property name="fooBar" ref="foo.bar.reference"/>
</bean>
This bean is meant to do things inside, get's properties passed by IoC but it is never used by any other bean which implies that the it's reference is nowhere else configured.
My problem is, that this bean seems not to be initialized because of that.
I tried <bean .. lazy-init="false"/> but this did not do the trick.
How can ensure the bean is going to be initialized?
Since I cannot modify the application context, I would need a way doing it just in the XML configuration.
I'm not sure, but maybe you could try to use the singleton=true property for that bean - in non-singleton mode, the bean would be instatiated only if requested by the application.
http://docs.spring.io/spring/docs/1.2.9/reference/beans.html
(see 3.2.5)
Edit: Can you add some logging to ctor to see if it's called? If not, could you add an init-method and log something there?
I have a spring injected service
class A{
List l = new ArrayList();
public m1(){
//do some additions in list
}
public m2(){
//do some new additions in list
}
}
Now because creating of objects of A, is in the hands of spring the behavior of program is not what is expected. (I expect list to be available empty always but not initialized by methods for some wired reason)
Will Spring always create only one instance of A, so that list l will keep on growing, I have configured bean as singleton in application context.
If yes, naturally I must initialize the list inside the functions m1 & m2 or callee must past the reference, and in my case callee being struts2 actions they are not singleton so this issue can be solved?
Or
Does spring provide any support in configuration to initialize member variables at every call or something else?
More generally what are best practices to have in writing services injected by spring about using member variables/ local variables for performance & efficiency.
Trying to answer following :
Does spring provide any support in configuration to initialize member variables at every call or something else?
By default Spring beans are singleton. Initialized only once and use the same object again and again.
However, if requirement changes as you asked. You need to understand scope attribute provided by the Spring.
<bean id="id" class="com.test.TP" scope="prototype">
</bean>
Refer following for detail understanding.
Scope Description
singleton
Scopes a single bean definition to a single object instance per
Spring IoC container.
prototype
Scopes a single bean definition to any number of object instances.
request
Scopes a single bean definition to the lifecycle of a single HTTP
request; that is each and every HTTP request will have its own
instance of a bean created off the back of a single bean definition.
Only valid in the context of a web-aware Spring ApplicationContext.
session
Scopes a single bean definition to the lifecycle of a HTTP Session.
Only valid in the context of a web-aware Spring ApplicationContext.
global session
Scopes a single bean definition to the lifecycle of a global HTTP
Session. Typically only valid when used in a portlet context. Only
valid in the context of a web-aware Spring ApplicationContext.
http://static.springsource.org/spring/docs/3.0.0.M3/spring-framework-reference/html/ch04s04.html
It is also possible to have user defined scope such as thread scope.
You can configure your bean as follows:-
<bean id = "serviceBeanA" class = "somepkg.A" scope="prototype">
<property name = "l">
<value>
<list>
<value>ABC</value>
.....
</list>
</value>
</property>
</bean>
I'm not sure if I understand the question but your sample class should work fine with spring. Spring will call the default constructor unless you pass in constructor args in the configuration file. As long as you have an id="..." in the bean then it will create a singleton of that class. Then, the first class that calls a.m1() will see l as being an empty list.
What may be happening is that you have multiple instances of A being created. See here about Spring singletons versus non. To quote:
Beans are defined to be deployed in one of two modes: singleton or non-singleton. (The latter is also called a prototype, although the term is used loosely as it doesn't quite fit). When a bean is a singleton, only one shared instance of the bean will be managed and all requests for beans with an id or ids matching that bean definition will result in that one specific bean instance being returned.
So if you don't have an id or name specified in your Spring configuration then you might get multiple instances of A created.
The non-singleton, prototype mode of a bean deployment results in the creation of a new bean instance every time a request for that specific bean is done. This is ideal for situations where for example each user needs an independent user object or something similar.
Lets say I have a situation like this:
<bean id="sample" class="ComlicatedClass" scope="prototype">
<property name="someProperty" value="${propertyValue}"/>
</bean>
I want to be able to create the bean programatically and provide value for propertyValue at runtime (pseudocode ahead):
appContext.getBean("sample", "propertyValue" => "value")
In a way, I want to create "bean template" rather than full defined bean. Is that possible in any way in spring?
EDIT:
The value for propertyValue is known at runtime! There is no way to define it as another bean.
why don't you just do
Sample sample = appContext.getBean("sample");
sample.setSomeProperty(appContext.getBean("someOtherBean"));
Have you looked at the Prototype scope?
The non-singleton, prototype scope of bean deployment results in the creation of a new bean instance every time a request for that specific bean is made. That is, the bean is injected into another bean or you request it through a getBean() method call on the container. As a rule, use the prototype scope for all stateful beans and the singleton scope for stateless beans.
There is also the #Scope annotation if you are using the Java based container configuration.
I have a custom scope defined for my Spring configuration, I want to initialize some of my beans "right after" my custom scope is created. At the moment my bean is not initialized because probably it is not called on right time when the scope is ready yet.
"myScope" is created through Java code.
<bean id="myAdvice" class="com.myclass" scope="myScope">
<property name="name1" ref="ref1" />
</bean>
"myScope" is created through Java code.
Well then either switch to XML or to Java-based configuration. If you do, your scope can have lifecycle callback methods, implement InitializingBean etc.
If you don't you have to do all that yourself programmatically when you initialize your scope. You would use applicationContext.getAutowireCapableBeanfactory() and use the AutowireCapableBeanFactory to wire the scope manually, using something like
AutowireCapableBeanFactory.initializeBean(Object, String) to post-process the scope (which will also execute any registered lifecycle callbacks).
I need to chance spring bean property values on runtime. Currently I'm doing it this way
Object bean = context.getBean(beanName);
BeanWrapper wrapper = PropertyAccessorFactory.forBeanPropertyAccess(bean);
wrapper.setPropertyValue(propertyName, newValue);
But some beans are configured as abstract
<bean id="abstractFoo" abstract="true" class="com.Foo" />
<bean id="bar" class="com.Bar">
<constructor-arg><bean parent="abstractFoo" /></constructor-arg>
</bean>
and in that case context.getBean("abstractFoo") throws BeanIsAbstractException
This is really simplified example, but I hope you get the idea.
Any idea how to change property value of abstract bean (in this case 'abstractFoo')?
We're using spring 2.5.4
Edit
Changed a XML example to be more specific. abstractFoo is declared abstract because of security reasons.
Spring application context contains bean definitions, and Spring instantiates bean objects defined by these definitions.
Your current code obtains an object that was created from the named bean definition, and changes its property. However, abstract beans are never instantiated as objects, they exist only in the form of definitions which are inherited by definitions of concrete beans.
So, if you want to change properties of abstract beans, you need to change their definitions, that can be done using BeanFactoryPostProcessor. Note, however, that post-processors are applied during container startup, so if you want it to be actually "runtime", you this approach is not applicable.
Disclaimer: this is untested; off the top of my head. Not sure if it will work after the init phase.
You need to get in instance of a ConfigurableListableBeanFactory. Your appcontext probably is one, so you can probably cast it.
From there, get the bean definition and change the property.
ConfigurableListableBeanFactory clbf = (ConfigurableListableBeanFactory)context;
BeanDefinition fooDefinition = clbf.getBeanDefinition("abstractFoo");
MutablePropertyValues pv = fooDefinition.getPropertyValues();
pv.add(propertyName, newValue);
Maybe you need to re-register your beandefinition with the ConfigurableListableBeanFactory after that. I'm not 100% sure; you'll have to test that.
Keep in mind that if it works, it will only work for beans that are instantiated after the change.